Maybe this is too late, but I had this problem recently and resolved the issue, here's what I did:
1) In the solution information, locate the error, it should state your error as well as the real set number that this is occurring in. Copy or write down that real set number.
2) Load up the solve.out file for your particular component system and search for that real set number. You'll find the contact pair that is identified with that real set number, which will tell you where the error is occurring.
3) From there, I would review the contact and check for any unusual conditions. Also, check the mesh over and make any modifications as necessary.
My mesh resolved and I even had success with this mesh in previous iterations, so there was nothing to indicate that my error was mesh related. However, simply changing a mesh refinement of mine to "soft" instead of "hard," resolved the issue in my case. In another case, I had to split faces and redefine the contact regions.
I hope this helps.
